Cancer is a significant healthcare issue for the world's population. As an example, liver cancer in adult men is the fifth most frequently diagnosed cancer worldwide, and is the second leading cause of cancer-related death in the world. Numerous therapeutic strategies have been employed in an effort to effectively treat cancer. Traditional therapeutic approaches have revolved around the use of chemotherapy and radiation therapy.
Chemotherapy refers to the administration of one or more anti-cancer drugs and/or other agents to a cancer patient by various methods. Broadly, most chemotherapeutic drugs work by impairing mitosis (cell division), effectively targeting fast-dividing cells. However, other fast dividing cells such as those responsible for hair growth and for replacement of the intestinal epithelium (lining) are also affected. Because chemotherapy affects cell division, both normal and cancerous cells are susceptible to the cytotoxic effects of chemotherapeutic agents.
Radiation therapy refers to exposing a patient to high-energy radiation, including x-rays, gamma rays, and neutrons. This type of therapy includes without limitation external-beam therapy, internal radiation therapy, implant radiation, brachytherapy, systemic radiation therapy, and radiotherapy. External beam radiation may include three dimensional conformal radiation therapy, intensity modulated radiation therapy, and conformal proton beam radiation therapy. In practice it is difficult to shield the nearby normal tissue from the cytotoxic effects of the radiation and still deliver a therapeutic dose. An additional complication of radiation is the induction of radiation resistant cells during the course of treatment. Thus, even the best radiotherapeutic techniques often result in incomplete tumor reduction and subsequent recurrence.
More recently, immunotherapeutic approaches have been employed in an attempt to harness the power of the host's immune system to treat cancer. For example, strategies have been employed to target cancer-associated antigens with host-based T cells that specifically recognize such antigens. For example, a recent approach has focused on the development and use of chimeric antigen receptor (CAR) T cells (also known as CAR-T cells). Possible side effects associated with CAR-T cell therapy include chemokine-release syndrome, B cell aplasia, and tumor lysis syndrome. Despite the development of these approaches, cancer remains a significant healthcare issue.